Add an API that reads multiple ranges from any number of sources

[vuule]

There are IO implementations that can optimize reading of multiple, scattered, ranges. Some example are io_uring and multihandle libcurl APIs. Currently kvikIO can only benefit from these within large reads (that get sliced into 4MB calls). When kvikIO gets a large number of small read calls, they all have to be handled separately and kvikIO cannot effectively use multihandle IO APIs.

Adding an API to kvikIO that handles reading of multiple ranges in a single call would allow optimizations in the use cases where the ranges cannot be coalesced on the caller side (e.g. highly selective Parquet reads).

TBD concrete API definition.

[kingcrimsontianyu]

Additional notes

This issue is related to #828 but on a potentially greater scale: requesting batch I/O capability, for local and remote respectively.
KvikIO's existing BatchHandle wraps the cuFile batch I/O APIs for GDS support. For our needs, the missing puzzles are:

• io_uring-based batch I/O for local, non-GDS file read/write. Initial implementation is by [26.04+ experimental] Add io_uring backend to improve I/O performance in general #870. Terminology clarification: io_uring is not part of POSIX.
• Libcurl multi-API for remote file read. Two paradigms: poll-based (initial implementation by Add a new remote I/O backend based on libcurl poll-based multi API #896), and event-driven (pending further assessment).
• For each file handle, we need to have a member method to accept a vector of ranges (offset, size).
• More generally, we need to have a function that batches the I/O requests from different file handles. There needs to be a mechanism to dissolve file handle boundaries.